Experimental Study On Static And Dynamic Testing Technology Of T-Shaped Rigid Frame Bridge

On the one hand, as a bridge to extend the service period, the volume of traffic (especially the ultra-tonnage vehicles) continues to increase, in addition to the original design, construction, materials, technology, conditions, and many other reasons, so that the existing bridge had varying degrees of injury; on the other hand, the original low road technical standards, the carrying capacity of highway bridges designed according to the original technical standards can not meet the needs of modern traffic. According to data indicate that part of the existing bridge has been classified as Dangerous Bridges, and a considerable part of aging, damage and significantly reduced the use of functions. If the bridge damage detection and monitoring is poor, which may result in the bridge collapse accident and death of people, even to the country's enormous economic losses.For the functional damage and existing imperfect bridges, we must first determine the actual carrying capacity of the bridge, the live load level allowed accessing, to explore the potential capacity of the structure; followed by the failure of some bridge repair using the method of reinforcement meet the requirements. Those two types of disposal methods are both require for detection of the bridge. On the test basis, we can make an accurate assessment to the carrying capacity of the bridge.T-shaped rigid frame bridge is the bridge span structure (main beam) and Piers connected with the overall force characteristics of cantilever bridge. It is a bridge-building in a more unique structure, with beautiful appearance, small size, clearance under the bridge, and horizons broaden, simple and quick construction, low maintenance costs. Therefore, T-shaped rigid frame bridge in China has been widely used. To have a better grasp of the using of such a bridge, and to provide conservation and reinforcement based on the detection of such a bridge technology research is essential. Therefore, this paper centers around the T-shaped rigid frame bridge static and dynamic detection techniques to carry out research work.Nineties of the 20th century, scientific research workers have carried out a series of studies on the T-Frame Bridge reinforcement technology and dynamic properties. Although the researchers at home and abroad have carried out a series of studies on T-shaped rigid frame bridge designing, maintenance and reinforcement theory. but so far, the static and dynamic detection system of T-shaped rigid frame bridge has not yet formed.Identification of dynamic parameters of bridges mainly implement by using experimental modal analysis methods. The experimental modal analysis technique is the using of vibration testing, signal processing and parameter identification method to obtain dynamic characteristics of the structure characterization of the modal parameters of a dynamic analysis. By test the input excitation and output response of the structure, in the physical parameters of the unknown, by computer signal processing, parameter identification through vibration system to identify the modal parameters of the establishment of the structure of the modal model, a very intuitive understanding of modal structure of the vibration bands can be seen for structural design and retrofit design department to provide the basic parameters of the structural dynamics, structural analysis of vibration characteristics of the system, structural dynamic properties, such as optimizing the design and modification. It is because of experimental modal analysis technique works great practical value, making it the use of vibration theory to solve engineering problems of the most important and most widely used technical means.Traditional structure dynamic parameters identification methods have to measure the measuring point excitation and the dynamic time-history response curve at the same time, based on the frequency domain the frequency response function (FRF) or the time-domain impulse response function (IRF), the driving force of structural parameters identification. The main traditional structure dynamic parameters identification methods are Klosterman iterative method, Levy method, Fitting orthogonal polynomials method [32], optimizing the recognition method, time-domain complex exponential fitting, Ibrahim time domain method, ERA methods. Between the dynamic test of the bridge, it is impossible to collected the time-response of the exciting force. It requires that only used of the time-history response response of dynamic measuring points to identify the dynamic parameters of the bridge. So the traditional identification methods can not identify the dynamic parameters of bridges.At present, The main methods can be used to identify bridge dynamic parameters from the random responses are peak method, frequency-domain decomposition method, sequence analysis, a random sub-space method. But the theory for the T-shaped rigid frame bridge dynamic testing and modal analysis of system has not yet formed.In this paper, on the basis of in-depth analysis of the variational principle and the principle of minimum potential energy, a clear T-shaped rigid frame bridge with limited methods of solving the basic principles and steps. On this basis, the study summed up the MIDAS and the ANSYS finite element software of their respective characteristics. Finally, the actual set up of a T-shaped rigid frame bridge the MIDAS and the ANSYS finite element model.It determines the T-shaped rigid frame bridge cross-section of the static test and the test content. Base on the MIDAS computing model, the establishment to determine the efficiency of the load required to meet the load position. After determining the load location, it calculates the test load displacement and strain based on the MIDAS and the ANSYS calculation model. On the T-shaped rigid frame bridge with a static load test at the scene and collected a load test, the measuring point parameters of the static measurements. Finally, it assesses the condition of the bridge based on the measured parameters of the static structure.Based on the results of theoretical calculations to determine the T-shaped rigid frame bridge layout the location of power points and sampling frequency, of a real T-shaped rigid frame bridge dynamic test carried out. We have designed low-pass digital filter in response to the collected signal filtering. Finally, we identify the T-shaped rigid frame bridge before the third-order vibration mode and frequency using modal analysis method based on transmission rate. the accuracy is higher.